The rule you are looking for is under the initial description of shapeshifting on YS177: "Unless explicitly noted otherwise, shapeshifting may be done as a supplemental action." Since the two shapeshifting powers you mentioned don't explicitly note otherwise, use that rule.
Note that there are several shapeshifting powers that do specify action types, therefore taking precidence over the above:
* Modular Abilities: "You may shapeshift your form to take on a variety of abilities, taking a full action to change them around." (YS177)
* True Shapeshifting: "You may take on nearly any humanoid or beastly form as a supplemental action. Changing into something else—say, a tree, a vacuum cleaner, a water bed—takes a longer amount of time, usually several actions, or even minutes, depending on how different." (YS177)